The mortices intersect within the post, and the ends of the tenons are mitered to give them equal reach. These double tenons on the back cor
The desk sides are simply wide board rails with wide, single-shouldered tenons on their ends. After you cut the top rails to length, plow the 3/8-inch groove to hold the bottom. Just like the bottom of the sea chest, the bottom of this desk fits in a groove plowed into the lower edges of the top boards. Here, of course, the task of fitting is considerably simpler, in that there is no bevel to deal with.

To look good, the tenon shoulder needs to be quite sharp where it fits against the legs. To ensure that the saw cuts are sharp and straight across the wide shoulder, make a knife cut straight down across the grain, then shear out a V tilted onto the waste side of the line. Set your saw in this V groove to start, and it will run true and leave a crisp edge. You can bring out the waste wood quickly with a broad chisel by first splitting and then shearing out across the grain. If you have a rabbet plane, it will help you bring this broad tenon to its final smoothness. The chisel and plane both tend to splinter off the far ends of the wood. You can prevent this either by reversing directions before you get to the end or by prechiseling the end in a bevel down to the line. Pare off the ends of the tenon with a chisel to a miter Vie inch shy of the other tenon, leaving room for some shrinkage in the leg.

Before you assemble the legs and rails with drawbored pegs and glue, you may want to decorate the corners with a bead. You can cut this bead with a molding plane if you have one, or do just about as good a job with a flat-head wood screw set into a block of wood. The slot in the screw head acts as a cutter and will shave a sloping groove parallel to the corners in no time. Round off the outer edge with a plane and you have a perfect bead down the length of your work. This bead not only looks good when you first do it but also keeps the piece looking good longer as well. A sharp corner is easily dented by just the slightest pressure and soon looks ragged. A corner bead effectively moves the sharp line of the corner back from the edge so that it is less prone to wear.

Full-sized horizontal cross section of the mortice and tenon joints.
Thus far in our work, we have been dealing with surfaces that are not so wide that a single board of a readily available width can do the job. For the desktop here, as with most tabletops, the width is so great that the boards will need to be edge-joined. There are scads of variations on edge joints, but all of them are founded on getting the edges as closely matched as possible. The trick to getting this fit just right is to use a long-bodied jointer plane on both boards simultaneously as they are clamped together. When the two boards are folded outward after such planing, any sideways tilt in the plane will be corrected, and the surface will be perfectly flat. The downside to this technique of paired planing is that any rounding over in the length is not compensated for but is actually doubled. The easiest way to get the boards dead flat is to plane a slight lengthwise hollow, then bring down the ends in a final jointing.

When chopping the intersecting mortices through the posts, make the first mortice only as deep as the intersection. That way, the chisel cut